1. Field of the Invention
This invention relates to an optical beam modulation and deflection device used for causing a laser beam or other optical beam to scan the surface of an information recording medium for the purpose of writing in or reading out information, and more particularly to an optical beam modulation deflection device of the type wherein a light source (a semiconductor laser, light-emitting diode etc.) is mounted on a rotator and the rotating light beam from the light source is simultaneously modulated and deflected in the same device, characterized in that the optical beam is modulated by the driving current for the light source at the same time that it is deflected by the rotation of the rotator.
2. Description of the Prior Art
Laser light sources have the advantage that they are capable of generating optical beams which enjoy a degree of excellence in their spatial interference properties and spectral line brightness which is difficult to obtain with other kinds of light sources. Because of these advantages, laser light sources are presently finding numerous applications in optical reading and recording devices. Among optical reading devices to which laser light sources are applied, there are facsimile transmitters, automatic bar code readers (for reading bar-coded labels), film scratch detection devices etc. In the area of optical recording devices using laser light sources, there can be mentioned data recording devices for video disks, facsimile receivers etc. In the past, these laser using devices mainly employed such so-called gas lasers as He-Ne lasers, He-Cd lasers, Ar lasers and the like. In the case of gas lasers, however, not only is the light source itself large but it must be used together with a scanner and a deflector if it is to be employed in an optical beam scanning application. As a result, devices using gas lasers have tended to be large and costly. Recently, therefore, utilization of small, high-efficiency semiconductor lasers has been increasing rapidly. For example, Japanese Public Disclosure No. 125044/78 (published Nov. 1, 1978) discloses a device for forming straight scanning lines by rotating a semiconductor laser.
The semiconductor laser scanning device described in Public Disclosure No. 125044/78 has numerous advantages; it is compact, low in cost and is capable of both modulating and deflecting the optical beam without need of additional devices. The device does, however, suffer from certain defects which result from the fact that electric power for the rotating light source is supplied to the light source via brushes or from a generator. When brushes are used, there are the drawbacks that the semiconductor laser, which is easily damaged by electrical shock, may breakdown under the electrical noise generated by the brushes and that utilization over long periods is impossible because of wearing of the brushes. On the other hand, when a generator is used, there are the drawbacks that the large size of the generator required makes it necessary to use a high power motor for rotation of the semiconductor laser and that it is impossible to electrically adjust the various parts of the device with the motor stopped.